The inventor owns a 23' Bayliner cabin cruiser which he wanted to trailer often to several different locations and wanted to load onto the boat's trailer without any assistance. He therefore decided to design and build a boat centering guide system. Having done so in the basement of his home and then mounting the centering guide system on his boat's trailer, the inventor and his son took the boat and trailer down to the Ohio River where the inventor backed the boat off of the trailer into the river. He then successfully loaded the boat back on to the trailer. The son, while standing on the shore, watched the bow of the boat pass over the stern of the trailer and then push one of the side mounted guides down because the boat was not centered with the trailer. This action allowed the boat to pass over the side mounted guide instead of damaging it and or the boat as often happens with other systems. After the boat was cradled in the trailer the inventor then used the boats motor to move the stern of the boat sideways toward the center of the trailer and the side mounted guide that was still in a vertical position. As soon as the boat neared the center of the trailer the guide that had rotated down under the boat rotated back up to a vertical position, grabbed the side of the boat and pushed it toward the center of the trailer. The boat was then confined between the two side mounted centering guides. The inventor then drove the boat up toward the fixed standing guide to touch the mooring post. He did this in spite of the fact that the size of the boat prevented him from seeing the side mounted centering guides during the loading procedure except when moving the boat sideways to confine it in between the side mounted centering guides. Within the next few minutes, the inventor successfully unloaded and loaded the boat five times with no assistance. The son simply looked on in amazement as he knew just how difficult it is to load a boat in this manner, especially from a river with wind and current. The inventor encountered no problems in the effort.